Change something on a module page and a bar appears at the bottom of the screen, saying "Unsaved changes". It has two buttons: Save changes and Reset.
The bar is only there while there is something to save. After a successful save it stays for a moment, showing the time it saved, and then disappears.
One bar per page
There is no second save button anywhere on the page. That is deliberate: with several buttons for the same form you can never tell which one saves what.
Reset puts every field back to the values that are stored, and the bar disappears. Use it when you changed the wrong thing and do not want to hunt for what it was.
Nothing is saved in the background. If you close the tab or navigate away with the bar still showing, module pages ask you to confirm first.
Warning
Confirm that prompt and your unsaved changes are gone. There is no draft and no recovery.
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